201,429 research outputs found
Green's function method for single-particle resonant states in relativistic mean field theory
Relativistic mean field theory is formulated with the Green's function method
in coordinate space to investigate the single-particle bound states and
resonant states on the same footing. Taking the density of states for free
particle as a reference, the energies and widths of single-particle resonant
states are extracted from the density of states without any ambiguity. As an
example, the energies and widths for single-neutron resonant states in
Sn are compared with those obtained by the scattering phase-shift
method, the analytic continuation in the coupling constant approach, the real
stabilization method and the complex scaling method. Excellent agreements are
found for the energies and widths of single-neutron resonant states.Comment: 20 pages, 7 figure
Control of beam propagation in optically written waveguides beyond the paraxial approximation
Beam propagation beyond the paraxial approximation is studied in an optically
written waveguide structure. The waveguide structure that leads to
diffractionless light propagation, is imprinted on a medium consisting of a
five-level atomic vapor driven by an incoherent pump and two coherent spatially
dependent control and plane-wave fields. We first study propagation in a single
optically written waveguide, and find that the paraxial approximation does not
provide an accurate description of the probe propagation. We then employ
coherent control fields such that two parallel and one tilted Gaussian beams
produce a branched waveguide structure. The tilted beam allows selective
steering of the probe beam into different branches of the waveguide structure.
The transmission of the probe beam for a particular branch can be improved by
changing the width of the titled Gaussian control beam as well as the intensity
of the spatially dependent incoherent pump field.Comment: 10 pages, 9 figure
(1S)-1-phenylethanaminium 4-{[(1S,2S)-1-hydroxy-2,3-dihydro-1H,1'H-[2,2'-biinden]-2-yl]methyl}benzoate
Copyright 2012 © International Union of Crystallography.The title molecular salt, C8H12N+·C26H21O3-, contains a dimeric indane pharmacophore that demonstrates potent anti-inflammatory activity. The indane group of the anion exhibits some disorder about the [alpha]-C atom, which appears common to many structures containing this group. A model to account for the slight disorder was attempted, but this was deemed unsuccessful because applying bond-length constraints to all the bonds about the [alpha]-C atom led to instability in the refinement. The absolute configuration was determined crystallographically as S,S,S by anomalous dispersion methods with reference to both the Flack parameter and Bayesian statistics on Bijvoet differences. The configuration was also determined by an a priori knowledge of the absolute configuration of the (1S)-1-phenylethanaminium counter-ion. The molecules pack in the crystal structure to form an infinite two-dimensional hydrogen-bond network in the (100) plane of the unit cell
Vibration Modes and the Dynamic Behaviour of a Hydraulic Plunger Pump
© 2016 Tianxiao Zhang and Nong Zhang. Mechanical vibrations and flow fluctuation give rise to complex interactive vibration mechanisms in hydraulic pumps. The working conditions for a hydraulic pump are therefore required to be improved in the design stage or as early as possible. Considering the structural features, parameters, and operating environment of a hydraulic plunger pump, the vibration modes for two-degree-of-freedom system were established by using vibration theory and hydraulic technology. Afterwards, the analytical form of the natural frequency and the numerical solution of the steady-state response were deduced for a hydraulic plunger pump. Then, a method for the vibration analysis of a hydraulic pump was proposed. Finally, the dynamic responses of a hydraulic plunger pump are obtained through numerical simulation
Single-particle and Interaction Effects on the Cohesion and Transport and Magnetic Properties of Metal Nanowires at Finite Voltages
The single-particle and interaction effects on the cohesion, electronic
transport, and some magnetic properties of metallic nanocylinders have been
studied at finite voltages by using a generalized mean-field electron model.
The electron-electron interactions are treated in the self-consistent Hartree
approximation. Our results show the single-particle effect is dominant in the
cohesive force, while the nonzero magnetoconductance and magnetotension
coefficients are attributed to the interaction effect. Both single-particle and
interaction effects are important to the differential conductance and magnetic
susceptibility.Comment: 5 pages, 6 figure
Tunable near- to mid-infrared pump terahertz probe spectroscopy in reflection geometry
Strong-field mid-infrared pump--terahertz (THz) probe spectroscopy has been
proven as a powerful tool for light control of different orders in strongly
correlated materials. We report the construction of an ultrafast broadband
infrared pump--THz probe system in reflection geometry. A two-output optical
parametric amplifier is used for generating mid-infrared pulses with GaSe as
the nonlinear crystal. The setup is capable of pumping bulk materials at
wavelengths ranging from 1.2 m to 15 m and beyond, and detecting the
subtle, transient photoinduced changes in the reflected electric field of the
THz probe at different temperatures. As a demonstration, we present 15 m
pump--THz probe measurements of a bulk EuSbTe single crystal. A
transient change in the reflected THz electric field can be clearly resolved.
The widely tuned pumping energy could be used in mode-selective excitation
experiments and applied to many strongly correlated electron systems.Comment: 4 pages, 4 figure
Kilohertz QPO Frequency and Flux Decrease in AQL X-1 and Effect of Soft X-ray Spectral Components
We report on an RXTE/PCA observation of Aql X-1 during its outburst in March
1997 in which, immediately following a Type-I burst, the broad-band 2-10 keV
flux decreased by about 10% and the kilohertz QPO frequency decreased from
813+-3 Hz to 776+-4 Hz. This change in kHz QPO frequency is much larger than
expected from a simple extrapolation of a frequency-flux correlation
established using data before the burst. Meanwhile a very low frequency noise
(VLFN) component in the broad-band FFT power spectra with a fractional
root-mean-square (rms) amplitude of 1.2% before the burst ceased to exist after
the burst. All these changes were accompanied by a change in the energy
spectral shape. If we characterize the energy spectra with a model composed of
two blackbody (BB) components and a power law component, almost all the
decrease in flux was in the two BB components. We attribute the two BB
components to the contributions from a region very near the neutron star or
even the neutron star itself and from the accretion disk, respectively.Comment: 12 pages with 4 figures, accepted for publication in ApJ Letters,
typos corrected and references update
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