3,551 research outputs found
Distributions of the -matrix poles in Woods-Saxon and cut-off Woods-Saxon potentials
The positions of the -matrix poles are calculated in generalized
Woods-Saxon (GWS) potential and in cut-off generalized Woods-Saxon (CGWS)
potential. The solutions of the radial equations are calculated numerically for
the CGWS potential and analytically for GWS using the formalism of Gy. Bencze
\cite{[Be66]}. We calculate CGWS and GWS cases at small non-zero values of the
diffuseness in order to approach the square well potential and to be able to
separate effects of the radius parameter and the cut-off radius parameter. In
the case of the GWS potential the wave functions are reflected at the nuclear
radius therefore the distances of the resonant poles depend on the radius
parameter of the potential. In CGWS potential the wave function can be
reflected at larger distance where the potential is cut to zero and the
derivative of the potential does not exist. The positions of most of the
resonant poles do depend strongly on the cut-off radius of the potential, which
is an unphysical parameter. Only the positions of the few narrow resonances in
potentials with barrier are not sensitive to the cut-off distance. For the
broad resonances the effect of the cut-off can not be corrected by using a
suggested analytical form of the first order perturbation correction.Comment: Accepted by Nucl. Phys.
Trajectories of the S-matrix poles in Salamon-Vertse potential
The trajectories of S-matrix poles are calculated in the finite-range
phenomenological potential introduced recently by P. Salamon and T. Vertse
(SV). The trajectories of the resonance poles in this SV potential are compared
to the corresponding trajectories in a cut-off Woods-Saxon (WS) potential for
l>0. The dependence on the cut-off radius is demonstrated. The starting points
of the trajectories turn out to be related to the average ranges of the two
terms in the SV potential
Calculating broad neutron resonances in a cut-off Woods-Saxon potential
In a cut-off Woods-Saxon (CWS) potential with realistic depth -matrix
poles being far from the imaginary wave number axis form a sequence where the
distances of the consecutive resonances are inversely proportional with the
cut-off radius value, which is an unphysical parameter. Other poles lying
closer to the imaginary wave number axis might have trajectories with irregular
shapes as the depth of the potential increases. Poles being close repel each
other, and their repulsion is responsible for the changes of the directions of
the corresponding trajectories. The repulsion might cause that certain
resonances become antibound and later resonances again when they collide on the
imaginary axis. The interaction is extremely sensitive to the cut-off radius
value, which is an apparent handicap of the CWS potential.Comment: 5 pages, 3 figure
Curvature Correction in the Strutinsky's Method
Mass calculations carried out by Strutinsky's shell correction method are
based on the notion of smooth single particle level density. The smoothing
procedure is always performed using curvature correction. In the presence of
curvature correction a smooth function remains unchanged if smoothing is
applied. Two new curvature correction methods are introduced. The performance
of the standard and new methods are investigated using harmonic oscillator and
realistic potentials.Comment: 4 figures, submitted to Journal of Physics G: Nuclear and Particle
Physic
High concentration ferronematics in low magnetic fields
We investigated experimentally the magneto-optical and dielectric properties
of magnetic-nanoparticle-doped nematic liquid crystals (ferronematics). Our
studies focus on the effect of the very small orienting bias magnetic field
, and that of the nematic director pretilt at the boundary surfaces
in our systems sensitive to low magnetic fields. Based on the results we assert
that is not necessarily required for a detectable response to low
magnetic fields, and that the initial pretilt, as well as the aggregation of
the nanoparticles play an important (though not yet explored enough) role.Comment: 13 pages, 6 figure
Automated knowledge capture in 2D and 3D design environments
In Life Cycle Engineering, it is vital that the engineering knowledge for the product is captured throughout its life cycle in a formal and structured manner. This will allow the information to be referred to in the future by engineers who did not work on the original design but are wanting to understand the reasons that certain design decisions were made. In the past, attempts were made to try to capture this knowledge by having the engineer record the knowledge manually during a design session. However, this is not only time-consuming but is also disruptive to the creative process. Therefore, the research presented in this paper is concerned with capturing design knowledge automatically using a traditional 2D design environment and also an immersive 3D design environment. The design knowledge is captured by continuously and non-intrusively logging the user during a design session and then storing this output in a structured eXtensible Markup Language (XML) format. Next, the XML data is analysed and the design processes that are involved can be visualised by the automatic generation of IDEF0 diagrams. Using this captured knowledge, it forms the basis of an interactive online assistance system to aid future users who are carrying out a similar design task
Potential impacts of a Turkish EU-membership on agri-food markets
This paper examines possible impacts of a Turkish accession to the EU on the agricultural markets in Turkey and the EU. AGMEMOD, an econometric, dynamic, multi-market, partial equilibrium economic model for EU agriculture at Member State level, has been extended with a model for the Turkish agricultural sector and afterwards applied to gain quantitative insights into Turkish accession effects. To establish a model for Turkey, the implementation of the model equations required parameter estimates, or the specification of synthetic model parameters. A database with time series on Turkish agricultural production, market balances and prices, macroeconomic variables and policy variables was developed in order to estimate such model parameters and to build an operational Turkish agriculture sector model. Most results show that the dominant impact of the Turkish accession on Turkish agriculture is a reduction of domestic producer prices, which induces further market effects. The - mostly decoupled - CAP support payments will induce smaller incentives to increase production than those which Turkish farmers receive prior to the EU accession. In Turkey effects of accession to the EU will be mostly negative for crop producers (except for tobacco), whereas the consumers are expected to gain from lower market prices. In contrast, producers of sheep meat, broiler and dairy milk could gain from an accession due to lower feed costs
Clinical profile of vigabatrin as monotherapy for treatment of infantile spasms
Jason T Lerner1, Noriko Salamon2, Raman Sankar1,31Departments of Pediatrics, 2Radiological Sciences, 3Neurology, David Geffen School of Medicine, University of California Los Angeles and Mattel Children’s Hospital at UCLA, Los Angeles, CA, USAAbstract: Vigabatrin, the first therapeutic agent to be approved by the Food and Drug Administration for the treatment of infantile spasms, as well as for adjunctive use in the treatment of refractory complex partial epilepsy, represents an important advance for patients with difficult-to-manage epilepsy. This review summarizes the complex history, chemistry, and pharmacology, as well as the clinical data leading to the approval of vigabatrin for infantile spasms in the US. The long path to its approval reflects the visual system and white matter toxicity concerns with this agent. This review provides a brief description of these concerns, and the regulatory safety monitoring and mitigation systems that have been put in place to enhance benefit over risk.Keywords: vigabatrin, infantile spasms, monotherap
Antibound poles in cutoff Woods-Saxon and in Salamon-Vertse potentials
The motion of l=0 antibound poles of the S-matrix with varying potential
strength is calculated in a cutoff Woods-Saxon (WS) potential and in the
Salamon-Vertse (SV) potential, which goes to zero smoothly at a finite
distance. The pole position of the antibound states as well as of the
resonances depend on the cutoff radius, especially for higher node numbers. The
starting points (at potential zero) of the pole trajectories correlate well
with the range of the potential. The normalized antibound radial wave functions
on the imaginary k-axis below and above the coalescence point have been found
to be real and imaginary, respectively
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