2,022 research outputs found
Analytic Expression for Exact Ground State Energy Based on an Operator Method for a Class of Anharmonic Potentials
A general procedure based on shift operators is formulated to deal with
anharmonic potentials. It is possible to extract the ground state energy
analytically using our method provided certain consistency relations are
satisfied. Analytic expressions for the exact ground state energy have also
been derived specifically for a large class of the one-dimensional oscillator
with cubic-quartic anharmonic terms. Our analytical results can be used to
check the accuracy of existing numerical methods, for instance the method of
state-dependent diagonalization. Our results also agree with the asymptotic
behavior in the divergent pertubative expansion of quartic harmonic oscillator.Comment: LaTeX with six figure (gif) files; Submitted to Phys. Rev.
A unified approach for exactly solvable potentials in quantum mechanics using shift operators
We present a unified approach for solving and classifying exactly solvable
potentials. Our unified approach encompasses many well-known exactly solvable
potentials. Moreover, the new approach can be used to search systematically for
a new class of solvable potentials.Comment: RevTex, 8 page
Genetic learning based texture surface inspection
This paper presents a novel approach of visual inspection for texture surface defects. It is based on the measure of texture energy acquired by a kind if high performance 2D detection mask, which is learned by genetic algorithms. Experimental results of texture defect inspection on textile images are presented to illustrate the merit and feasibility of the proposed method.<br /
Genetic image enhancement based on saturation feedback
In this paper an adaptive approach for color image enhancement is proposed. In this approach, the saturation feedback technique is used as a means of supplementing color image shmpness and contrast. This technique of the saturation feedback can serve to bring out image details that have low luminance contrast. In the technique, the feedback parameters are the key component and are usually determined manually. In order to realize the adaptive color image enhancement, the genetic algorithm is employed to search global optimal parameters for saturation feedback automatically. The detailed procedures are described in the paper. Experimental results on color images show the feasibility of the proposed method.<br /
Mapping the Milky Way with LAMOST II: the stellar halo
The radial number density and flattening of the Milky Way's stellar halo is
measured with metal-poor ([Fe/H]) K giants from LAMOST
DR3, using a nonparametric method which is model independent and largely avoids
the influence of halo substucture. The number density profile is well described
by a single power law with index , and flattening that
varies with radius. The stellar halo traced by LAMOST K giants is more
flattened at smaller radii, and becomes nearly spherical at larger radii. The
flattening, , is about 0.64, 0.8, 0.96 at , 20 and 30 kpc (where
), respectively. Moreover, the
leading arm of the Sagittarius dwarf galaxy tidal stream in the north, and the
trailing arm in the south, are significant in the residual map of density
distribution. In addition, an unknown overdensity is identified in the residual
map at (R,Z)=(30,15) kpc.Comment: 16 pages, 24 figures, accepted by MNRA
Geometry and optics calibration of WFCTA prototype telescopes using star light
The Large High Altitude Air Shower Observatory project is proposed to study
high energy gamma ray astronomy ( 40 GeV-1 PeV ) and cosmic ray physics ( 20
TeV-1 EeV ). The wide field of view Cherenkov telescope array, as a component
of the LHAASO project, will be used to study energy spectrum and compositions
of cosmic ray by measuring the total Cherenkov light generated by air showers
and shower maximum depth. Two prototype telescopes have been in operation since
2008. The pointing accuracy of each telescope is crucial to the direction
reconstruction of the primary particles. On the other hand the primary energy
reconstruction relies on the shape of the Cherenkov image on the camera and the
unrecorded photons due to the imperfect connections between photomultiplier
tubes. UV bright stars are used as point-like objects to calibrate the pointing
and to study the optical properties of the camera, the spot size and the
fractions of unrecorded photons in the insensitive areas of the camera.Comment: 5 pages, 6 figures, submitted to Chinese Physics
Variation in both host defense and prior herbivory can alter plant-vector-virus interactions
Background:
While virus-vector-host interactions have been a major focus of both basic and applied ecological research, little is known about how different levels of plant defense interact with prior herbivory to affect these relationships. We used genetically-modified strains of tomato (Solanum lycopersicum) varying in the jasmonic acid (JA) plant defense pathways to explore how plant defense and prior herbivory affects a plant virus (tomato yellow leaf curl virus, ‘TYLCV’), its vector (the whitefly Bemisia tabaci MED), and the host.
Results:
Virus-free MED preferred low-JA over high-JA plants and had lower fitness on high-JA plants. Viruliferous MED preferred low-JA plants but their survival was unaffected by JA levels. While virus-free MED did not lower plant JA levels, viruliferous MED decreased both JA levels and the expression of JA-related genes. Infestation by viruliferous MED reduced plant JA levels. In preference tests, neither virus-free nor viruliferous MED discriminated among JA-varying plants previously exposed to virus-free MED. However, both virus-free and viruliferous MED preferred low-JA plant genotypes when choosing between plants that had both been previously exposed to viruliferous MED. The enhanced preference for low-JA genotypes appears linked to the volatile compound neophytadiene, which was found only in whitefly-infested plants and at concentrations inversely related to plant JA levels.
Conclusions:
Our findings illustrate how plant defense can interact with prior herbivory to affect both a plant virus and its whitefly vector, and confirm the induction of neophytadiene by MED. The apparent attraction of MED to neophytadiene may prove useful in pest detection and management
Isostructural Phase Transition of TiN Under High Pressure
In situ high-pressure energy dispersive x-ray diffraction experiments on
polycrystalline powder TiN with NaCl-type structure have been conducted with
the pressure up to 30.1 GPa by using the diamond anvil cell instrument with
synchrotron radiation at room tempearture. The experimental results suggested
that an isostructural phase transition might exist at about 7 GPa as revealed
by the discontinuity of V/V0 with pressure.Comment: submitte
Total Reaction Cross Section in an Isospin-Dependent Quantum Molecular Dynamics (IDQMD) Model
The isospin-dependent quantum molecular dynamics (IDQMD) model is used to
study the total reaction cross section . The energy-dependent Pauli
volumes of neutrons and protons have been discussed and introduced into the
IDQMD calculation to replace the widely used energy-independent Pauli volumes.
The modified IDQMD calculation can reproduce the experimental well
for both stable and exotic nuclei induced reactions. Comparisons of the
calculated induced by with different initial density
distributions have been performed. It is shown that the calculation by using
the experimentally deduced density distribution with a long tail can fit the
experimental excitation function better than that by using the
Skyrme-Hartree-Fock calculated density without long tails. It is also found
that at high energy is sensitive to the long tail of density
distribution.Comment: 4 page, 4 fig
Safety and Short-Term Toxicity of a Novel Cationic Lipid Formulation for Human Gene Therapy
Overview summary Although several viral vectors have been widely applied to the treatment of human disease, the development of nonviral vectors is still in their infancy. In this report, a novel cationic lipid, DMRIE/DOPE, has been incorporated into the DNA–liposome formulation that improves transfection efficiencies and allows up to 1,000-fold higher concentrations of DNA to be administered in vivo. In this paper, the safety and toxicity of this formulation is described in two species, mice and pigs, suggesting that it may prove useful for human gene therapy.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/63224/1/hum.1993.4.6-781.pd
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