423 research outputs found
Investigation of activation cross-sections of proton induced nuclear reactions on natTl up to 42 MeV: review, new data and evaluation
Cross-sections of proton induced nuclear reactions on natural thallium have
been studied for investigation of the production of the medical important 201Tl
diagnostic radioisotope. The excitation functions of 204mPb, 203Pb, 202mPb,
201Pb, 200Pb, 199Pb, 202Tl (direct, cumulative), 201Tl (direct, cumulative),
200Tl(direct), and 203Hg were measured up to 42 MeV proton energy by stacked
foil technique and activation method. The experimental data were compared with
the critically analyzed experimental data in the literature, with the IAEA
recommended data and with the results of model calculations by using the
ALICE-IPPE, EMPIRE-II and TALYS codes
Compilation of isomeric ratios of light particle induced nuclear reactions
Experimental isomeric ratios of light (A4) particle-induced nuclear
reactions were compiled for the product nuclides having metastable states with
half-lives longer than 0.1 sec. The experimental isomeric ratio data were taken
from the EXFOR library and reviewed. When an experiment reports isomer
production cross sections instead of isomeric ratios, the cross sections taken
from the EXFOR library were converted to the isomeric ratios by us. During
compilation, questionable data (e.g.,preliminary data compiled in EXFOR in
parallel with their final data, sum of isomer production cross sections larger
than the total production cross sections) were excluded. As an application of
the new compilation, goodness-of-fit was studied for the isomeric ratios
predicted by the reaction model code TALYS-1.96
Latrocimicinae completes the phylogeny of Cimicidae: meeting old morphologic data rather than modern host phylogeny.
The family Cimicidae includes obligate hematophagous ectoparasites (bed bugs and their relatives) with high veterinary/medical importance. The evolutionary relationships of Cimicidae and their hosts have recently been reported in a phylogenetic context, but in the relevant study, one of the six subfamilies, the bat-specific Latrocimicinae, was not represented. In this study the only known species of Latrocimicinae, i.e., Latrocimex spectans, was analyzed with molecular and phylogenetic methods based on four (two nuclear and two mitochondrial) genetic markers. The completed subfamily-level phylogeny of Cimicidae showed that Latrocimicinae is most closely related to Haematosiphoninae (ectoparasites of birds and humans), with which it shares systematically important morphologic characters, but not hosts. Moreover, in the phylogenetic analyses, cimicid bugs that are known to infest phylogenetically distant bat hosts clustered together (e.g., Leptocimex and Stricticimex within Cacodminae), while cimicid subfamilies (Latrocimicinae, Primicimicinae) that are known to infest bat hosts from closely related superfamilies clustered distantly. In conclusion, adding Latrocimicinae significantly contributed to the resolution of the phylogeny of Cimicidae. The close phylogenetic relationship between Latrocimicinae and Haematosiphoninae is consistent with long-known morphologic data. At the same time, phylogenetic relationships of genera within subfamilies are inconsistent with the phylogeny of relevant hosts
Excited state g-functions from the Truncated Conformal Space
In this paper we consider excited state g-functions, that is, overlaps
between boundary states and excited states in boundary conformal field theory.
We find a new method to calculate these overlaps numerically using a variation
of the truncated conformal space approach. We apply this method to the Lee-Yang
model for which the unique boundary perturbation is integrable and for which
the TBA system describing the boundary overlaps is known. Using the truncated
conformal space approach we obtain numerical results for the ground state and
the first three excited states which are in excellent agreement with the TBA
results. As a special case we can calculate the standard g-function which is
the overlap with the ground state and find that our new method is considerably
more accurate than the original method employed by Dorey et al.Comment: 21 pages, 6 figure
Casimir effect in the boundary state formalism
Casimir effect in the planar setting is described using the boundary state
formalism, for general partially reflecting boundaries. It is expressed in
terms of the low-energy degrees of freedom, which provides a large distance
expansion valid for general interacting field theories provided there is a
non-vanishing mass gap. The expansion is written in terms of the scattering
amplitudes, and needs no ultraviolet renormalization. We also discuss the case
when the quantum field has a nontrivial vacuum configuration.Comment: 11 pages. Proceedings contribution of talk given at the Workshop on
Quantum Field Theory under the Influence of External Conditions (QFEXT07),
University of Leipzig, September 16-21, 2007. To appear in J. Phys.
Form-factors of the sausage model obtained with bootstrap fusion from sine-Gordon theory
We continue the investigation of massive integrable models by means of the
bootstrap fusion procedure, started in our previous work on O(3) nonlinear
sigma model. Using the analogy with SU(2) Thirring model and the O(3) nonlinear
sigma model we prove a similar relation between sine-Gordon theory and a
one-parameter deformation of the O(3) sigma model, the sausage model. This
allows us to write down a free field representation for the
Zamolodchikov-Faddeev algebra of the sausage model and to construct an integral
representation for the generating functions of form-factors in this theory. We
also clear up the origin of the singularities in the bootstrap construction and
the reason for the problem with the kinematical poles.Comment: 16 pages, revtex; references added, some typos corrected. Accepted
for publication in Physical Review
Persistence exponents of non-Gaussian processes in statistical mechanics
Motivated by certain problems of statistical physics we consider a stationary
stochastic process in which deterministic evolution is interrupted at random
times by upward jumps of a fixed size. If the evolution consists of linear
decay, the sample functions are of the "random sawtooth" type and the level
dependent persistence exponent \theta can be calculated exactly. We then
develop an expansion method valid for small curvature of the deterministic
curve. The curvature parameter g plays the role of the coupling constant of an
interacting particle system. The leading order curvature correction to \theta
is proportional to g^{2/3}. The expansion applies in particular to exponential
decay in the limit of large level, where the curvature correction considerably
improves the linear approximation. The Langevin equation, with Gaussian white
noise, is recovered as a singular limiting case.Comment: 20 pages, 3 figure
Free field representation for the O(3) nonlinear sigma model and bootstrap fusion
The possibility of the application of the free field representation developed
by Lukyanov for massive integrable models is investigated in the context of the
O(3) sigma model. We use the bootstrap fusion procedure to construct a free
field representation for the O(3) Zamolodchikov- Faddeev algebra and to write
down a representation for the solutions of the form-factor equations which is
similar to the ones obtained previously for the sine-Gordon and SU(2) Thirring
models. We discuss also the possibility of developing further this
representation for the O(3) model and comment on the extension to other
integrable field theories.Comment: 14 pages, latex, revtex v3.0 macro package, no figures Accepted for
publication in Phys. Rev.
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