782 research outputs found
Biallelic and Genome Wide Association Mapping of Germanium Tolerant Loci in Rice (Oryza sativa L.)
Funding: This project was partially funded by a Biotechnology and Biological Sciences Research Council (BBSRC) grant (BB/J003336/1) awarded to AHP. The work was also supported by a self-funded studentship (PT). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.Peer reviewedPublisher PD
Implications of surface noise for the motional coherence of trapped ions
Electric noise from metallic surfaces is a major obstacle towards quantum
applications with trapped ions due to motional heating of the ions. Here, we
discuss how the same noise source can also lead to pure dephasing of motional
quantum states. The mechanism is particularly relevant at small ion-surface
distances, thus imposing a new constraint on trap miniaturization. By means of
a free induction decay experiment, we measure the dephasing time of the motion
of a single ion trapped 50~m above a Cu-Al surface. From the dephasing
times we extract the integrated noise below the secular frequency of the ion.
We find that none of the most commonly discussed surface noise models for ion
traps describes both, the observed heating as well as the measured dephasing,
satisfactorily. Thus, our measurements provide a benchmark for future models
for the electric noise emitted by metallic surfaces.Comment: (5 pages, 4 figures
Continuous Correction of Differential Path Length Factor in Near-Infrared Spectroscopy
In continuous-wave near-infrared spectroscopy (CW-NIRS), changes in the concentration of oxyhemoglobin and deoxyhemoglobin can be calculated by solving a set of linear equations from the modified Beer-Lambert Law. Cross-talk error in the calculated hemodynamics can arise from inaccurate knowledge of the wavelength-dependent differential path length factor (DPF). We apply the extended Kalman filter (EKF) with a dynamical systems model to calculate relative concentration changes in oxy- and deoxyhemoglobin while simultaneously estimating relative changes in DPF. Results from simulated and experimental CW-NIRS data are compared with results from a weighted least squares (WLSQ) method. The EKF method was found to effectively correct for artificially introduced errors in DPF and to reduce the cross-talk error in simulation. With experimental CW-NIRS data, the hemodynamic estimates from EKF differ significantly from the WLSQ (p\u3c0.001 ). The cross-correlations among residuals at different wavelengths were found to be significantly reduced by the EKF method compared to WLSQ in three physiologically relevant spectral bands 0.04 to 0.15 Hz, 0.15 to 0.4 Hz and 0.4 to 2.0 Hz (p\u3c0.001 ). This observed reduction in residual cross-correlation is consistent with reduced cross-talk error in the hemodynamic estimates from the proposed EKF method
On the supersymmetric nonlinear evolution equations
Supersymmetrization of a nonlinear evolution equation in which the bosonic
equation is independent of the fermionic variable and the system is linear in
fermionic field goes by the name B-supersymmetrization. This special type of
supersymmetrization plays a role in superstring theory. We provide
B-supersymmetric extension of a number of quasilinear and fully nonlinear
evolution equations and find that the supersymmetric system follows from the
usual action principle while the bosonic and fermionic equations are
individually non Lagrangian in the field variable. We point out that
B-supersymmetrization can also be realized using a generalized Noetherian
symmetry such that the resulting set of Lagrangian symmetries coincides with
symmetries of the bosonic field equations. This observation provides a basis to
associate the bosonic and fermionic fields with the terms of bright and dark
solitons. The interpretation sought by us has its origin in the classic work of
Bateman who introduced a reverse-time system with negative friction to bring
the linear dissipative systems within the framework of variational principle.Comment: 12 pages, no figure
QTL-seq reveals a major root-knot nematode resistance locus on chromosome 11 in rice (Oryza sativa L.)
Open Access via Springer Compact Agreement. This project was funded by FAACE-JPI NET project “GreenRice” (Sustainable and environmental friendly rice cultivation systems in Europe); BBSRC award BB/M018415/1. The authors would like to acknowledge the support of the Maxwell computer cluster funded by the University of Aberdeen for sequencing work and the financial support of GOA 01GB3013 from Ghent University.Peer reviewedPublisher PD
Solution of the relativistic Dirac-Hulthen problem
The one-particle three-dimensional Dirac equation with spherical symmetry is
solved for the Hulthen potential. The s-wave relativistic energy spectrum and
two-component spinor wavefunctions are obtained analytically. Conforming to the
standard feature of the relativistic problem, the solution space splits into
two distinct subspaces depending on the sign of a fundamental parameter in the
problem. Unique and interesting properties of the energy spectrum are pointed
out and illustrated graphically for several values of the physical parameters.
The square integrable two-component wavefunctions are written in terms of the
Jacobi polynomials. The nonrelativistic limit reproduces the well-known
nonrelativistic energy spectrum and results in Schrodinger equation with a
"generalized" three-parameter Hulthen potential, which is the sum of the
original Hulthen potential and its square.Comment: 13 pages, 3 color figure
Trapped ions in optical lattices for probing oscillator chain models
We show that a chain of trapped ions embedded in microtraps generated by an
optical lattice can be used to study oscillator models related to dry friction
and energy transport. Numerical calculations with realistic experimental
parameters demonstrate that both static and dynamic properties of the ion chain
change significantly as the optical lattice power is varied. Finally, we lay
out an experimental scheme to use the spin degree of freedom to probe the phase
space structure and quantum critical behavior of the ion chain
Bulk and Boundary Critical Behavior at Lifshitz Points
Lifshitz points are multicritical points at which a disordered phase, a
homogeneous ordered phase, and a modulated ordered phase meet. Their bulk
universality classes are described by natural generalizations of the standard
model. Analyzing these models systematically via modern
field-theoretic renormalization group methods has been a long-standing
challenge ever since their introduction in the middle of the 1970s. We survey
the recent progress made in this direction, discussing results obtained via
dimensionality expansions, how they compare with Monte Carlo results, and open
problems. These advances opened the way towards systematic studies of boundary
critical behavior at -axial Lifshitz points. The possible boundary critical
behavior depends on whether the surface plane is perpendicular to one of the
modulation axes or parallel to all of them. We show that the semi-infinite
field theories representing the corresponding surface universality classes in
these two cases of perpendicular and parallel surface orientation differ
crucially in their Hamiltonian's boundary terms and the implied boundary
conditions, and explain recent results along with our current understanding of
this matter.Comment: Invited contribution to STATPHYS 22, to be published in the
Proceedings of the 22nd International Conference on Statistical Physics
(STATPHYS 22) of the International Union of Pure and Applied Physics (IUPAP),
4--9 July 2004, Bangalore, Indi
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