4,304 research outputs found
A novel expression cassette for the efficient visual selection of transformed tissues in florists' chrysanthemum (Chrysanthemum morifolium Ramat.).
Constructs carrying visual reporter genes coupled with efficient promoters could facilitate the process of identification and selection of stable transformants in recalcitrant crops. Here, a novel construct utilizing a ribulose-1,5-bisphosphate carboxylase (RbcS) promoter combined with the green fluorescent protein (GFP) reporter gene to initiate very high expression of GFP in florist's chrysanthemum (Chrysanthemum morifolium Ramat.) was described. Based on this expression cassette, a new regeneration protocol using leaf discs as explants was developed for the Agrobacterium-mediated transformation of Chrysanthemum genotype ‘1581’, and a transformation efficiency of 7% was obtained. The expression of two different GFP constructs targeted to either cytosol or plastids was compared in transgenic lines. Both GFP constructs were expressed at such a high level that the green fluorescence dominated red fluorescence in the leaf tissues, allowing easy observation and microdissection of transformed tissues even without a GFP filter. Under normal light, plants with GFP targeted to plastids had a light green phenotype deriving from the high GFP expression. Quantitative reverse transcriptional PCR analysis showed that the plastid targeted construct with intron had significantly higher steady state transcript levels of GFP mRNA. This novel expression cassette may allow direct visual selection of transformed tissues independent of antibiotic selection in a wide range of plant specie
Calculation of electronic properties of amorphous alloys
We describe the application of the
locally-self-consistent-multiple-scattering (LSMS)[1] method to amorphous
alloys. The LSMS algorithm is optimized for the Intel XP/S-150, a
multiple-instruction-multiple-data parallel computer with 1024 nodes and 2
compute processors per node. The electron density at each site is determined by
solving the multiple scattering equation for atoms within a specified distance
of the atom under consideration. Because this method is carried out in real
space it is ideal for treating amorphous alloys. We have adapted the code to
the calculation of the electronic properties of amorphous alloys. In these
calculations we determine the potentials in the atomic sphere approximation
self consistently at each site, unlike previous calculations[2] where we
determined the potentials self consistently at an average site. With these
self-consistent potentials, we then calculate electronic properties of various
amorphous alloy systems. We present calculated total electronic densities of
states for amorphous NiP and NiPdP with 300
atoms in a supercell.Comment: 10 pages, plain tex, 2 figures. Paper accepted for publication in
Proceedings of LAM-9 and Journal of non-Crystalline Solids. Please request
preprints from J.C. Swihart ([email protected]
Quantum State Reconstruction of Many Body System Based on Complete Set of Quantum Correlations Reduced by Symmetry
We propose and study a universal approach for the reconstruction of quantum
states of many body systems from symmetry analysis. The concept of minimal
complete set of quantum correlation functions (MCSQCF) is introduced to
describe the state reconstruction. As an experimentally feasible physical
object, the MCSQCF is mathematically defined through the minimal complete
subspace of observables determined by the symmetry of quantum states under
consideration. An example with broken symmetry is analyzed in detail to
illustrate the idea.Comment: 10 pages, n figures, Revte
Ground State and Spectral Properties of a Quantum Impurity in d-Wave Superconductors
The variational approach of Gunnarsson and Sch\"onhammer to the Anderson
impurity model is generalized to study d-wave superconductors in the presence
of dilute spin-1/2 impurities. We show that the local moment is screened when
the hybridization exceeds a nonzero critical value at which the ground state
changes from a spin doublet to a spin singlet. The electron spectral functions
are calculated in both phases. We find that while a Kondo resonance develops
above the Fermi level in the singlet phase, the spectral function exhibits a
low-energy spectral peak below the Fermi level in the spin doublet phase. The
origin of such a ``virtual Kondo resonance'' is the existence of low-lying
collective excitations in the spin-singlet sector. We discuss our results in
connection to recent spectroscopic experiments on Zn doped high-T
superconductors.Comment: 5 pages, 4figures, revised versio
Nonohmic conductivity as a probe of crossover from diffusion to hopping in two dimensions
We show that the study of conductivity nonlinearity gives a possibility to
determine the condition when the diffusion conductivity changes to the hopping
one with increasing disorder. It is experimentally shown that the conductivity
of single quantum well GaAs/InGaAs/GaAs heterostructures behaves like diffusive
one down to value of order .Comment: 4 pages, 2 figure
Gold adatoms and dimers on relaxed graphite surfaces
The interaction of deposited gold adatoms and dimers with multilayer relaxed graphite surfaces is investigated through a density functional approach with numerical orbitals and a relativistic core pseudopotential. The energy landscape for a gold adatom along [110] agrees with scanning tunneling microscopy observations including the preferred β binding site for adatoms and the mobility difference between silver and gold adatoms. Deposited particles are shown to induce surface deformation and polarization. Static relaxation and dynamic simulations indicate that the energetically preferred binding orientation for a gold dimer is normal rather than parallel to the graphite surface. The dimer response to a simulated scanning tunneling microscopy tip is investigated by molecular dynamics simulations
Stationary and Transient Work-Fluctuation Theorems for a Dragged Brownian Particle
Recently Wang et al. carried out a laboratory experiment, where a Brownian
particle was dragged through a fluid by a harmonic force with constant velocity
of its center. This experiment confirmed a theoretically predicted work related
integrated (I) Transient Fluctuation Theorem (ITFT), which gives an expression
for the ratio for the probability to find positive or negative values for the
fluctuations of the total work done on the system in a given time in a
transient state. The corresponding integrated stationary state fluctuation
theorem (ISSFT) was not observed. Using an overdamped Langevin equation and an
arbitrary motion for the center of the harmonic force, all quantities of
interest for these theorems and the corresponding non-integrated ones (TFT and
SSFT, resp.) are theoretically explicitly obtained in this paper. While the
(I)TFT is satisfied for all times, the (I)SSFT only holds asymptotically in
time. Suggestions for further experiments with arbitrary velocity of the
harmonic force and in which also the ISSFT could be observed, are given. In
addition, a non-trivial long-time relation between the ITFT and the ISSFT was
discovered, which could be observed experimentally, especially in the case of a
resonant circular motion of the center of the harmonic force.Comment: 20 pages, 3 figure
Novel approaches for rescuing function of the salivary gland epithelium in primary Sjögren's syndrome
Primary Sjögren's syndrome (pSS) is a systemic autoimmune disease characterised by dysfunction and inflammatory lymphocytic infiltration of exocrine glands, namely the salivary and lacrimal glands. pSS patients often suffer from sicca (dry mouth) complaints, including dental caries, and difficulties in eating, sleeping and speaking. A large body of literature points to a central role for salivary gland (SG) epithelial cells in the development of this pathology. Here we summarise recent studies concerning the role of SG epithelial cells in pSS, which strongly indicate their intrinsic activation and early involvement during the disease process. Based on that, we propose possible future interventions targeting SG epithelial cells, to treat SG dysfunction pSS
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