434 research outputs found
Kink dynamics in a novel discrete sine-Gordon system
A spatially-discrete sine-Gordon system with some novel features is
described. There is a topological or Bogomol'nyi lower bound on the energy of a
kink, and an explicit static kink which saturates this bound. There is no
Peierls potential barrier, and consequently the motion of a kink is simpler,
especially at low speeds. At higher speeds, it radiates and slows down.Comment: 10 pages, 7 figures, archivin
Novel Technique for Ultra-sensitive Determination of Trace Elements in Organic Scintillators
A technique based on neutron activation has been developed for an extremely
high sensitivity analysis of trace elements in organic materials. Organic
materials are sealed in plastic or high purity quartz and irradiated at the
HFIR and MITR. The most volatile materials such as liquid scintillator (LS) are
first preconcentrated by clean vacuum evaporation. Activities of interest are
separated from side activities by acid digestion and ion exchange. The
technique has been applied to study the liquid scintillator used in the KamLAND
neutrino experiment. Detection limits of <2.4X10**-15 g 40K/g LS, <5.5X10**-15
g Th/g LS, and <8X10**-15 g U/g LS have been achieved.Comment: 16 pages, 3 figures, accepted for publication in Nuclear Instruments
and Methods
A (2+1) dimensional integrable spin model: Geometrical and gauge equivalent counterpart, solitons and localized coherent structures
A non-isospectral (2+1) dimensional integrable spin equation is investigated.
It is shown that its geometrical and gauge equivalent counterparts is the (2+1)
dimensional nonlinear Schr\"odinger equation introduced by Zakharov and studied
recently by Strachan. Using a Hirota bilinearised form, line and curved soliton
solutions are obtained. Using certain freedom (arbitrariness) in the solutions
of the bilinearised equation, exponentially localized dromion-like solutions
for the potential is found. Also, breaking soliton solutions (for the spin
variables) of the shock wave type and algebraically localized nature are
constructed.Comment: 14 pages, LaTex, no figures; email of first author:
[email protected] and [email protected]
Deformation surfaces, integrable systems and Chern - Simons theory
A few years ago, some of us devised a method to obtain integrable systems in
(2+1)-dimensions from the classical non-Abelian pure Chern-Simons action via
reduction of the gauge connection in Hermitian symmetric spaces. In this paper
we show that the methods developed in studying classical non-Abelian pure
Chern-Simons actions, can be naturally implemented by means of a geometrical
interpretation of such systems. The Chern-Simons equation of motion turns out
to be related to time evolving 2-dimensional surfaces in such a way that these
deformations are both locally compatible with the Gauss-Mainardi-Codazzi
equations and completely integrable. The properties of these relationships are
investigated together with the most relevant consequences. Explicit examples of
integrable surface deformations are displayed and discussed.Comment: 24 pages, 1 figure, submitted to J. Math. Phy
Solitons in anharmonic chains with ultra-long-range interatomic interactions
We study the influence of long-range interatomic interactions on the
properties of supersonic pulse solitons in anharmonic chains. We show that in
the case of ultra-long-range (e.g., screened Coulomb) interactions three
different types of pulse solitons coexist in a certain velocity interval: one
type is unstable but the two others are stable. The high-energy stable soliton
is broad and can be described in the quasicontinuum approximation. But the
low-energy stable soliton consists of two components, short-range and
long-range ones, and can be considered as a bound state of these components.Comment: 4 pages (LaTeX), 5 figures (Postscript); submitted to Phys. Rev.
Towards Minimal S4 Lepton Flavor Model
We study lepton flavor models with the flavor symmetry. We construct
simple models with smaller numbers of flavon fields and free parameters, such
that we have predictions among lepton masses and mixing angles. The model with
a triplet flavon is not realistic, but we can construct realistic models
with two triplet flavons, or one triplet and one doublet flavons.Comment: 18 pages, 4 figures, references are adde
Discrete symmetries and models of flavor mixing
Evidences of a discrete symmetry behind the pattern of lepton mixing are
analyzed. The program of "symmetry building" is outlined. Generic features and
problems of realization of this program in consistent gauge models are
formulated. The key issues include the flavor symmetry breaking, connection of
mixing and masses, {\it ad hoc} prescription of flavor charges, "missing"
representations, existence of new particles, possible accidental character of
the TBM mixing. Various ways are considered to extend the leptonic symmetries
to the quark sector and to reconcile them with Grand Unification. In this
connection the quark-lepton complementarity could be a viable alternative to
TBM. Observational consequences of the symmetries and future experimental tests
of their existence are discussed.Comment: 14 pages, 5 figures. Talk given at the Symposium "DISCRETE 2010", 6 -
11 December 2010, La Sapienza, Rome, Ital
Fermion masses and mixing with tri-bimaximal in SO(10) with type-I seesaw
We study a class of models for tri-bimaximal neutrino mixing in SO(10) grand
unified SUSY framework. Neutrino masses arise from both type-I and type-II
seesaw mechanisms. We use dimension five operators in order to not spoil
tri-bimaximal mixing by means of type-I contribution in the neutrino sector. We
show that it is possible to fit all fermion masses and mixings including also
the recent T2K result as deviation from the tri-bimaximal.Comment: 13 pages, journal version, minor comments and reference adde
Separation of Variables in the Classical Integrable SL(3) Magnetic Chain
There are two fundamental problems studied by the theory of hamiltonian
integrable systems: integration of equations of motion, and construction of
action-angle variables. The third problem, however, should be added to the
list: separation of variables. Though much simpler than two others, it has
important relations to the quantum integrability. Separation of variables is
constructed for the magnetic chain --- an example of integrable model
associated to a nonhyperelliptic algebraic curve.Comment: 13 page
Examining Treatment Decision-Making Among Patients With Axial Spondyloarthritis: Insights From a Conjoint Analysis Survey
OBJECTIVE: The number of therapies for axial spondyloarthritis (axSpA) is increasing. Thus, it has become more challenging for patients and physicians to navigate the risk-benefit profiles of the various treatment options. In this study, we used conjoint analysis-a form of trade-off analysis that elucidates how people make complex decisions by balancing competing factors-to examine patient decision-making surrounding medication options for axSpA.
METHODS: We conducted an adaptive choice-based conjoint analysis survey for patients with axSpA to assess the relative importance of medication attributes (eg, chance of symptom improvement, risk of side effects, route of administration, etc) in their decision-making. We also performed logistic regression to explore whether patient demographics and disease characteristics predicted decision-making.
RESULTS: Overall, 397 patients with axSpA completed the conjoint analysis survey. Patients prioritized medication efficacy (importance score 26.8%), cost (26.3%), and route of administration (13.9%) as most important in their decision-making. These were followed by risk of lymphoma (9.5%), dosing frequency (7.2%), risk of serious infection (6.0%), tolerability of side effects (5.3%), and clinic visit and laboratory test frequency (4.8%). In regression analyses, there were few significant associations between patients\u27 treatment preferences and sociodemographic and axSpA characteristics.
CONCLUSIONS: Treatment decision-making in axSpA is highly individualized, and demographics and baseline disease characteristics are poor predictors of individual preferences. This calls for the development of online shared decision-making tools for patients and providers, with the goal of selecting a treatment that is consistent with patients\u27 preferences
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