2,574 research outputs found
Discovery of a large set of SNP and SSR genetic markers by high-throughput sequencing of pepper (Capsicum annuum)
Genetic markers based on single nucleotide polymorphisms (SNPs) are in increasing demand for genome mapping and fingerprinting of breeding populations in crop plants. Recent advances in high-throughput sequencing provide the opportunity for whole-genome resequencing and identification of allelic variants by mapping the reads to a reference genome. However, for many species, such as pepper (Capsicum annuum), a reference genome sequence is not yet available. To this end, we sequenced the C. annuum cv. "Yolo Wonder" transcriptome using Roche 454 pyrosequencing and assembled de novo 23,748 isotigs and 60,370 singletons. Mapping of 10,886,425 reads obtained by the Illumina GA II sequencing of C. annuum cv. "Criollo de Morclos 334" to the "Yolo Wonder" transcriptome allowed for SNP identification. By setting a threshold value that allows selecting reliable SNPs with minimal loss of information, 11,849 reliable SNPs spread across 5919 isotigs were identified. In addition, 853 single sequence repeats were obtained. This information has been made available online
Gradient Representations and Affine Structures in AE(n)
We study the indefinite Kac-Moody algebras AE(n), arising in the reduction of
Einstein's theory from (n+1) space-time dimensions to one (time) dimension, and
their distinguished maximal regular subalgebras sl(n) and affine A_{n-2}^{(1)}.
The interplay between these two subalgebras is used, for n=3, to determine the
commutation relations of the `gradient generators' within AE(3). The low level
truncation of the geodesic sigma-model over the coset space AE(n)/K(AE(n)) is
shown to map to a suitably truncated version of the SL(n)/SO(n) non-linear
sigma-model resulting from the reduction Einstein's equations in (n+1)
dimensions to (1+1) dimensions. A further truncation to diagonal solutions can
be exploited to define a one-to-one correspondence between such solutions, and
null geodesic trajectories on the infinite-dimensional coset space H/K(H),
where H is the (extended) Heisenberg group, and K(H) its maximal compact
subgroup. We clarify the relation between H and the corresponding subgroup of
the Geroch group.Comment: 43 page
Symmetries,Singularities and the De-Emergence of Space
Recent work has revealed intriguing connections between a
Belinsky-Khalatnikov-Lifshitz-type analysis of spacelike singularities in
General Relativity and certain infinite dimensional Lie algebras, and in
particular the `maximally extended' hyperbolic Kac--Moody algebra E10. In this
essay we argue that these results may lead to an entirely new understanding of
the (quantum) nature of space(-time) at the Planck scale, and hence -- via an
effective `de-emergence' of space near a singularity -- to a novel mechanism
for achieving background independence in quantum gravity.Comment: 10 page
Quantum State Engineering with Continuous-Variable Post-Selection
We present a scheme to conditionally engineer an optical quantum system via
continuous-variable measurements. This scheme yields high-fidelity squeezed
single photon and superposition of coherent states, from input single and two
photon Fock states respectively. The input Fock state is interacted with an
ancilla squeezed vacuum state using a beam-splitter. We transform the quantum
system by post-selecting on the continuous-observable measurement outcome of
the ancilla state. We experimentally demonstrate the principles of this scheme
using displaced coherent states and measure experimentally fidelities that are
only achievable using quantum resources.Comment: 4 pages, 5 figures, publishe
The influence of bond-rigidity and cluster diffusion on the self-diffusion of hard spheres with square-well interaction
Hard spheres interacting through a square-well potential were simulated using
two different methods: Brownian Cluster Dynamics (BCD) and Event Driven
Brownian Dynamics (EDBD). The structure of the equilibrium states obtained by
both methods were compared and found to be almost the identical. Self diffusion
coefficients () were determined as a function of the interaction strength.
The same values were found using BCD or EDBD. Contrary the EDBD, BCD allows one
to study the effect of bond rigidity and hydrodynamic interaction within the
clusters. When the bonds are flexible the effect of attraction on is
relatively weak compared to systems with rigid bonds. increases first with
increasing attraction strength, and then decreases for stronger interaction.
Introducing intra-cluster hydrodynamic interaction weakly increases for a
given interaction strength. Introducing bond rigidity causes a strong decrease
of which no longer shows a maximum as function of the attraction strength
Conditional quantum-state engineering using ancillary squeezed-vacuum states
We investigate an optical scheme to conditionally engineer quantum states
using a beam splitter, homodyne detection and a squeezed vacuum as an ancillar
state. This scheme is efficient in producing non-Gaussian quantum states such
as squeezed single photons and superpositions of coherent states (SCSs). We
show that a SCS with well defined parity and high fidelity can be generated
from a Fock state of , and conjecture that this can be generalized for
an arbitrary Fock state. We describe our experimental demonstration of this
scheme using coherent input states and measuring experimental fidelities that
are only achievable using quantum resources.Comment: 10 pages, 14 figures, use pdf version, high quality figures available
on reques
Relativistic entanglement of two massive particles
We describe the spin and momentum degrees of freedom of a system of two
massive spin-- particles as a 4 qubit system. Then we explicitly
show how the entanglement changes between different partitions of the qubits,
when considered by different inertial observers. Although the two particle
entanglement corresponding to a partition into Alice's and Bob's subsystems is,
as often stated in the literature, invariant under Lorentz boosts, the
entanglement with respect to other partitions of the Hilbert space on the other
hand, is not. It certainly does depend on the chosen inertial frame and on the
initial state considered. The change of entanglement arises, because a Lorentz
boost on the momenta of the particles causes a Wigner rotation of the spin,
which in certain cases entangles the spin- with the momentum states. We
systematically investigate the situation for different classes of initial spin
states and different partitions of the 4 qubit space.
Furthermore, we study the behavior of Bell inequalities for different
observers and demonstrate how the maximally possible degree of violation, using
the Pauli-Lubanski spin observable, can be recovered by any inertial observer.Comment: 17 pages, 4 figure
Supersymmetric quantum cosmological billiards
D=11 Supergravity near a space-like singularity admits a cosmological
billiard description based on the hyperbolic Kac-Moody group E10. The
quantization of this system via the supersymmetry constraint is shown to lead
to wavefunctions involving automorphic (Maass wave) forms under the modular
group W^+(E10)=PSL(2,O) with Dirichlet boundary conditions on the billiard
domain. A general inequality for the Laplace eigenvalues of these automorphic
forms implies that the wave function of the universe is generically complex and
always tends to zero when approaching the initial singularity. We discuss
possible implications of this result for the question of singularity resolution
in quantum cosmology and comment on the differences with other approaches.Comment: 4 pages. v2: Added ref. Version to be published in PR
Gauged diffeomorphisms and hidden symmetries in Kaluza-Klein theories
We analyze the symmetries that are realized on the massive Kaluza-Klein modes
in generic D-dimensional backgrounds with three non-compact directions. For
this we construct the unbroken phase given by the decompactification limit, in
which the higher Kaluza-Klein modes are massless. The latter admits an
infinite-dimensional extension of the three-dimensional diffeomorphism group as
local symmetry and, moreover, a current algebra associated to SL(D-2,R)
together with the diffeomorphism algebra of the internal manifold as global
symmetries. It is shown that the `broken phase' can be reconstructed by gauging
a certain subgroup of the global symmetries. This deforms the three-dimensional
diffeomorphisms to a gauged version, and it is shown that they can be governed
by a Chern-Simons theory, which unifies the spin-2 modes with the Kaluza-Klein
vectors. This provides a reformulation of D-dimensional Einstein gravity, in
which the physical degrees of freedom are described by the scalars of a gauged
non-linear sigma model based on SL(D-2,R)/SO(D-2), while the metric appears in
a purely topological Chern-Simons form.Comment: 23 pages, minor changes, v3: published versio
Photon creation in a spherical oscillating cavity
We study the photon creation inside a perfectly conducting, spherical
oscillating cavity. The electromagnetic field inside the cavity is described by
means of two scalar fields which satisfy Dirichlet and (generalized) Neumann
boundary conditions. As a preliminary step, we analyze the dynamical Casimir
effect for both scalar fields. We then consider the full electromagnetic case.
The conservation of angular momentum of the electromagnetic field is also
discussed, showing that photons inside the cavity are created in singlet
states.Comment: 14 pages, no figure
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