404 research outputs found
Improved switching table for direct power control of three-phase PWM rectifier
The switching table based direct power control (ST-DPC) of three-phase PWM rectifier is analysed and an improved switching table (IST-DPC) is presented. The proposed switching schedule improves the quality of line current and results in better dynamic performances. In addition, the predictive direct power control (PDPC) of three-phase boost rectifier is presented and simulation results (in MATLAB/SIMULINK environment) are compared with those generated by ST-DPC and ISD-DPC approaches. Advantages and limitations of each control scheme are highlighted and conclusions regarding applications, quality of current waveforms and burden of calculations are presented
Fast non-negative deconvolution for spike train inference from population calcium imaging
Calcium imaging for observing spiking activity from large populations of
neurons are quickly gaining popularity. While the raw data are fluorescence
movies, the underlying spike trains are of interest. This work presents a fast
non-negative deconvolution filter to infer the approximately most likely spike
train for each neuron, given the fluorescence observations. This algorithm
outperforms optimal linear deconvolution (Wiener filtering) on both simulated
and biological data. The performance gains come from restricting the inferred
spike trains to be positive (using an interior-point method), unlike the Wiener
filter. The algorithm is fast enough that even when imaging over 100 neurons,
inference can be performed on the set of all observed traces faster than
real-time. Performing optimal spatial filtering on the images further refines
the estimates. Importantly, all the parameters required to perform the
inference can be estimated using only the fluorescence data, obviating the need
to perform joint electrophysiological and imaging calibration experiments.Comment: 22 pages, 10 figure
Tests and applications of self-consistent cranking in the interacting boson model
The self-consistent cranking method is tested by comparing the cranking
calculations in the interacting boson model with the exact results obtained
from the SU(3) and O(6) dynamical symmetries and from numerical
diagonalization. The method is used to study the spin dependence of shape
variables in the and boson models. When realistic sets of parameters
are used, both models lead to similar results: axial shape is retained with
increasing cranking frequency while fluctuations in the shape variable
are slightly reduced.Comment: 9 pages, 3 ps figures, Revte
Mechanistic Insights in the Success of Fecal Microbiota Transplants for the Treatment of Clostridium difficile Infections
Molecular basis of bacterial pathogenesis, virulence factors and antibiotic resistanc
Microscopic Study of Superdeformed Rotational Bands in 151Tb
Structure of eight superdeformed bands in the nucleus 151Tb is analyzed using
the results of the Hartree-Fock and Woods-Saxon cranking approaches. It is
demonstrated that far going similarities between the two approaches exist and
predictions related to the structure of rotational bands calculated within the
two models are nearly parallel. An interpretation scenario for the structure of
the superdeformed bands is presented and predictions related to the exit spins
are made. Small but systematic discrepancies between experiment and theory,
analyzed in terms of the dynamical moments, J(2), are shown to exist. The
pairing correlations taken into account by using the particle-number-projection
technique are shown to increase the disagreement. Sources of these systematic
discrepancies are discussed -- they are most likely related to the yet not
optimal parametrization of the nuclear interactions used.Comment: 32 RevTeX pages, 15 figures included, submitted to Physical Review
Time-odd components in the mean field of rotating superdeformed nuclei
Rotation-induced time-odd components in the nuclear mean field are analyzed
using the Hartree-Fock cranking approach with effective interactions SIII,
SkM*, and SkP. Identical dynamical moments are obtained for
pairs of superdeformed bands Tb(2)--Dy(1) and
Gd(2)--Tb(1). The corresponding relative alignments strongly
depend on which time-odd mean-field terms are taken into account in the
Hartree-Fock equations.Comment: 23 pages, ReVTeX, 6 uuencoded postscript figures include
Magnetic moments of 2 1 + states in 124,126,128 Sn
The g factors of the first-excited states of stable 124Sn and radioactive 126,128Sn were measured by the recoil-in-vacuum method with comparatively high precision. The experiments were performed at the Holifield Radioactive Ion Beam Facility by Coulomb e
Theoretical description of deformed proton emitters: nonadiabatic coupled-channel method
The newly developed nonadiabatic method based on the coupled-channel
Schroedinger equation with Gamow states is used to study the phenomenon of
proton radioactivity. The new method, adopting the weak coupling regime of the
particle-plus-rotor model, allows for the inclusion of excitations in the
daughter nucleus. This can lead to rather different predictions for lifetimes
and branching ratios as compared to the standard adiabatic approximation
corresponding to the strong coupling scheme. Calculations are performed for
several experimentally seen, non-spherical nuclei beyond the proton dripline.
By comparing theory and experiment, we are able to characterize the angular
momentum content of the observed narrow resonance.Comment: 12 pages including 10 figure
Superdeformation in the Doubly Magic Nucleus 40Ca
A rotational band with seven gamma -ray transitions between states with spin 2 (h) over bar and 16 (h) over bar has been observed in the doubly magic, self-conjugate nucleus Ca-40(20)20. The measured transition quadrupole moment of 1.80(-0.29)(+0.39)eb indicates a superdeformed shape with a deformation beta (2) = 0.59(-0.07)(+0.11). The features of this band are explained by cranked relativistic mean field calculations to arise from an 8-particle 8-hole excitation
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