137 research outputs found
A Method for Solving a Class of Multiple-Criteria Analysis Problems
AMS subject classification: 90C29.The paper proposes an interactive method solving the multiple criteria choice problem (MCCP) with a large number of discrete alternatives and a small number of
quantitative criteria. The decision maker (DM) sets his preferences in terms of
desired directions of improving or relaxing of the criteria. On this base the so
called reference cone is constructed. A small subset of relatively closed alternatives
is defined according to this cone and to the maximal deterioration of the criteria
values at each iteration. This subset is evaluated by the DM, who selects the most
preferred alternative or enters his/her new preferences.
The method suggested has user-friendly dialog. It enables the DM to explore
the set of alternatives comparatively quickly and easy. The method is included in
a DSS. It is tested by a number of real multiple criteria choice problems
R-matrix presentation for (super)-Yangians Y(g)
We give a unified RTT presentation of (super)-Yangians Y(g) for so(n), sp(2n)
and osp(m|2n).Comment: 9 page
Relativistic Quantum Thermodynamics of Ideal Gases in 2 Dimensions
In this work we study the behavior of relativistic ideal Bose and Fermi gases
in two space dimensions. Making use of polylogarithm functions we derive a
closed and unified expression for their densities. It is shown that both type
of gases are essentially inequivalent, and only in the non-relativistic limit
the spinless and equal mass Bose and Fermi gases are equivalent as known in the
literature.Comment: 6 pages, 1 figur
Magnetic and electric dipole moments of the state in ThO
The metastable state in the thorium monoxide (ThO)
molecule is highly sensitive to the presence of a CP-violating permanent
electric dipole moment of the electron (eEDM). The magnetic dipole moment
and the molecule-fixed electric dipole moment of this state are
measured in preparation for a search for the eEDM. The small magnetic moment
displays the predicted cancellation of
spin and orbital contributions in a paramagnetic molecular
state, providing a significant advantage for the suppression of magnetic field
noise and related systematic effects in the eEDM search. In addition, the
induced electric dipole moment is shown to be fully saturated in very modest
electric fields ( 10 V/cm). This feature is favorable for the suppression of
many other potential systematic errors in the ThO eEDM search experiment.Comment: 4 pages, 3 figure
Quantum-Classical Correspondence of Dynamical Observables, Quantization and the Time of Arrival Correspondence Problem
We raise the problem of constructing quantum observables that have classical
counterparts without quantization. Specifically we seek to define and motivate
a solution to the quantum-classical correspondence problem independent from
quantization and discuss the general insufficiency of prescriptive
quantization, particularly the Weyl quantization. We demonstrate our points by
constructing time of arrival operators without quantization and from these
recover their classical counterparts
Low temperature electrical transport in microwave plasma fabricated free-standing graphene and N-graphene sheets
Funding Information: This work was performed under the framework of the PEGASUS (Plasma Enabled and Graphene Allowed Synthesis of Unique nano-Structures) project, funded by the European Unionâs Horizon research and innovation program under grant agreement No 766894. Work partially funded by Portuguese FCT - Fundação para a CiĂȘncia e a Tecnologia, through EAGER project (PTDC/NAN-MAT/30565/2017) and under projects UIDB/50010/2020 and UIDP/50010/2020. The authors would like to thank S. Russev for the SEM images. M A, E V, K K and Zh K thank the European Regional Development Fund within the Operational Programme âScience and Education for Smart Growth 2014â2020â under the Project CoE âNational center of mechatronics and clean technologies âBG05M2OP001-1.001-0008â. Publisher Copyright: © 2023 The Author(s). Published by IOP Publishing Ltd.In this paper, the electrical transport in free-standing graphene and N-graphene sheets fabricated by a microwave plasma-based method is addressed. Temperature-dependent resistivity/conductivity measurements are performed on the graphene/N-graphene sheets compressed in pellets. Different measurement configurations reveal directional dependence of current flowâthe room-temperature conductivity longitudinal to the pelletâs plane is an order of magnitude higher than the transversal one, due to the preferential orientation of graphene sheets in the pellets. SEM imaging confirms that the graphene sheets are mostly oriented parallel to the pelletâs plane and stacked in agglomerates. The high longitudinal electrical conductivity with values on the order of 103 S/m should be noted. Further, the current flow mechanism revealed from resistivity-temperature dependences from 300K down to 10K shows non-metallic behavior manifested with an increasing resistivity with decreasing the temperature d Ï / d T < 0 usually observed for insulating or localized systems. The observed charge transport shows variable range hopping at lower temperatures and thermally activated behaviour at higher temperatures. This allows us to attribute the charge transport mechanism to a partially disordered system in which single graphene sheets are placed predominantly parallel to each other and stacked together.publishersversionpublishe
Epidemiology of hip fractures in Bulgaria : development of a country-specific FRAX model
Summary
A retrospective population-based survey was undertaken in a region of Bulgaria to determine the incidence of hip fracture. The estimated number of hip fractures nationwide for 2015 was 9322 and is predicted to increase to 11,398 in 2050. The hip fracture rates were used to create a FRAX model.
Objective
To describe the epidemiology of hip fractures in Bulgaria, which was then used to develop the country-specific fracture prediction FRAXÂź tool.
Methods
We carried out a retrospective population-based survey in Stara Zagora, Bulgaria, representing approximately 4.6% of the countryâs population. We identified hip fractures occurring in 2015, 2016 and 2017 from hospital registers and primary care sources held by the regional health insurance agency. Age- and sex-specific incidence of hip fracture and national mortality rates were incorporated into a FRAX model for Bulgaria. Fracture probabilities were compared with those from neighbouring countries having FRAX models.
Results
The incidence of hip fracture applied nationally suggested that the estimated number of hip fractures nationwide in persons over the age of 50 years for 2015 was 9322 and is predicted to increase to 11,398 in 2050. FRAX-based probabilities were higher in Bulgaria than those in Serbia or Romania, lower than those in Turkey and similar to those in Greece.
Conclusion
The FRAX model should enhance accuracy of determining fracture probability among the Bulgarian population and help guide decisions about treatment
Integrable Structure of Conformal Field Theory, Quantum KdV Theory and Thermodynamic Bethe Ansatz
We construct the quantum versions of the monodromy matrices of KdV theory.
The traces of these quantum monodromy matrices, which will be called as ``-operators'', act in highest weight Virasoro modules. The -operators depend on the spectral parameter and their expansion
around generates an infinite set of commuting Hamiltonians
of the quantum KdV system. The -operators can be viewed as the
continuous field theory versions of the commuting transfer-matrices of
integrable lattice theory. In particular, we show that for the values
of the Virasoro central charge
the eigenvalues of the -operators satisfy a closed system of
functional equations sufficient for determining the spectrum. For the
ground-state eigenvalue these functional equations are equivalent to those of
massless Thermodynamic Bethe Ansatz for the minimal conformal field theory
; in general they provide a way to generalize the technique
of Thermodynamic Bethe Ansatz to the excited states. We discuss a
generalization of our approach to the cases of massive field theories obtained
by perturbing these Conformal Field Theories with the operator .
The relation of these -operators to the boundary states is also
briefly described.Comment: 24 page
New remarks on the linear constraint self-dual boson and Wess-Zumino terms
In this work we prove in a precise way that the soldering formalism can be
applied to the Srivastava chiral boson (SCB), in contradiction with some
results appearing in the literature. We have promoted a canonical
transformation that shows directly that the SCB is composed of two
Floreanini-Jackiw's particles with the same chirality which spectrum is a
vacuum-like one. As another conflictive result we have proved that a
Wess-Zumino term used in the literature consists of the scalar field, once
again denying the assertion that the WZ term adds a new degree of freedom to
the SCB theory in order to modify the physics of the system.Comment: 6 pages, Revtex. Final version to appear in Physical Review
Spin physics with antiprotons
New possibilities arising from the availability at GSI of antiproton beams,
possibly polarised, are discussed. The investigation of the nucleon structure
can be boosted by accessing in Drell-Yan processes experimental asymmetries
related to cross-sections in which the parton distribution functions (PDF) only
appear, without any contribution from fragmentation functions; such processes
are not affected by the chiral suppression of the transversity function
. Spin asymmetries in hyperon production and Single Spin Asymmetries
are discussed as well, together with further items like electric and magnetic
nucleonic form factors and open charm production. Counting rates estimations
are provided for each physical case. The sketch of a possible experimental
apparatus is proposed.Comment: Presented for the proceedings of ASI "Spin and Symmetry", Prague,
July 5-10, 2004, to be published in Czech. J. Phys. 55 (2005
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