Momentum Space Integral Equations for Three Charged Particles: Diagonal Kernels

It has been a long-standing question whether momentum space integral equations of the Faddeev type are applicable to reactions of three charged particles, in particular above the three-body threshold. For, the presence of long-range Coulomb forces has been thought to give rise to such severe singularities in their kernels that the latter may lack the compactness property known to exist in the case of purely short-range interactions. Employing the rigorously equivalent formulation in terms of an effective-two-body theory we have proved in a preceding paper [Phys. Rev. C {\bf 61}, 064006 (2000)] that, for all energies, the nondiagonal kernels occurring in the integral equations which determine the transition amplitudes for all binary collision processes, possess on and off the energy shell only integrable singularities, provided all three particles have charges of the same sign, i.e., all Coulomb interactions are repulsive. In the present paper we prove that, for particles with charges of equal sign, the diagonal kernels, in contrast, possess one, but only one, nonintegrable singularity. The latter can, however, be isolated explicitly and dealt with in a well-defined manner. Taken together these results imply that modified integral equations can be formulated, with kernels that become compact after a few iterations. This concludes the proof that standard solution methods can be used for the calculation of all binary (i.e., (in-)elastic and rearrangement) amplitudes by means of momentum space integral equations of the effective-two-body type.Comment: 36 pages, 2 figures, accepted for publication in Phys. Rev.

Triangle Diagram with Off-Shell Coulomb T-Matrix for (In-)Elastic Atomic and Nuclear Three-Body Processes

The driving terms in three-body theories of elastic and inelastic scattering of a charged particle off a bound state of two other charged particles contain the fully off-shell two-body Coulomb T-matrix describing the intermediate-state Coulomb scattering of the projectile with each of the charged target particles. Up to now the latter is usually replaced by the Coulomb potential, either when using the multiple-scattering approach or when solving three-body integral equations. General properties of the exact and the approximate on-shell driving terms are discussed, and the accuracy of this approximation is investigated numerically, both for atomic and nuclear processes including bound-state excitation, for energies below and above the corresponding three-body dissociation threshold, over the whole range of scattering angles.Comment: 22 pages, 11 figures, figures can be obtained upon request from the Authors, revte

Proton-Deuteron Elastic Scattering from 2.5 to 22.5 MeV

We present the results of a calculation of differential cross sections and polarization observables for proton-deuteron elastic scattering, for proton laboratory energies from 2.5 to 22.5 MeV. The Paris potential parametrisation of the nuclear force is used. As solution method for the charged-composite particle equations the 'screening and renormalisation approach' is adopted which allows to correctly take into account the Coulomb repulsion between the two protons. Comparison is made with the precise experimental data of Sagara et al. [Phys. Rev. C 50, 576 (1994)] and of Sperison et al. [Nucl. Phys. A422, 81 (1984)].Comment: 24 pages, 8 eps figures, uses REVTe

Long-range behavior of the optical potential for the elastic scattering of charged composite particles

The asymptotic behavior of the optical potential, describing elastic scattering of a charged particle $\alpha$ off a bound state of two charged, or one charged and one neutral, particles at small momentum transfer $\Delta_{\alpha}$ or equivalently at large intercluster distance $\rho_{\alpha}$, is investigated within the framework of the exact three-body theory. For the three-charged-particle Green function that occurs in the exact expression for the optical potential, a recently derived expression, which is appropriate for the asymptotic region under consideration, is used. We find that for arbitrary values of the energy parameter the non-static part of the optical potential behaves for $\Delta_{\alpha} \rightarrow 0$ as $C_{1}\Delta_{\alpha} + o\,(\Delta_{\alpha})$. From this we derive for the Fourier transform of its on-shell restriction for $\rho_{\alpha} \rightarrow \infty$ the behavior $-a/2\rho_{\alpha}^4 + o\,(1/\rho_{\alpha}^4)$, i.e., dipole or quadrupole terms do not occur in the coordinate-space asymptotics. This result corroborates the standard one, which is obtained by perturbative methods. The general, energy-dependent expression for the dynamic polarisability $C_{1}$ is derived; on the energy shell it reduces to the conventional polarisability $a$ which is independent of the energy. We emphasize that the present derivation is {\em non-perturbative}, i.e., it does not make use of adiabatic or similar approximations, and is valid for energies {\em below as well as above the three-body dissociation threshold}.Comment: 35 pages, no figures, revte

Scattering theory for arbitrary potentials

The fundamental quantities of potential scattering theory are generalized to accommodate long-range interactions. New definitions for the scattering amplitude and wave operators valid for arbitrary interactions including potentials with a Coulomb tail are presented. It is shown that for the Coulomb potential the generalized amplitude gives the physical on-shell amplitude without recourse to a renormalization procedure.Comment: To be published in Phys Rev

Potential role of galanine in the treatment of type 2 diabetes mellitus

The growing incidence of diabetes mellitus requires the optimizing of existing approaches and searching for new ones to treat this disease. It is necessary to study the features of other regulators that play a significant role in the process of glucose uptake by cells, along with the insulin resistance caused by defects in the molecular mechanisms of insulin action. Galanine, a neuropeptide of 29 (30 in humans) amino acids, is involved in a large number of different vital functions, including regulating energy metabolism in the cell. Galanine interacts with three G protein-coupled receptors, GAL1, GAL2, and GAL3, and transmitting signals through several transduction pathways, including cAMP/PKA inhibition (GAL1, GAL3) and phospholipase C (GAL2) stimulation. Agonists and antagonists of galanine receptor subtype GalR1-3 can be used as intended therapeutic targets to treat various human diseases. We accumulated more data that prove the importance of the galanine peptide regulator in the etiology of impaired glucose uptake by insulin-dependent tissues. The review considers such effects of galanine, as inhibition of insulin synthesis, activation of expression and translocation to the plasma cell membrane of the glucose transporter GLUT4, increase of PPAR-g level, and decrease in duodenal hyper-contractility. These data confirm the importance of research to find an effective antidiabetic drug among the synthesized analogs of galanine

Исследование сорбции лекарственных веществ перфтораном

Objective: to estimate the perfluorane adsorption capacity of the drugs belonging to different pharmacological groups. Materials and methods. The binding of perfluorane to 50 drugs at concentrations of 12.5 to 100 ^M was studied in vitro using equilibrium dialysis. Results. Interactions of ligands with the particles of perfluorane emulsion were found to be of three types. Type 1 substances were characterized by negative affinity to perfluorane; type 2 ligands acted indifferently with the emulsion; type 3 compounds were reversibly adsorbed with the particles of the blood substitute by the affinity constants ( Kaff) of 104 M-1. Conclusion. The perfluorane adsorption capacity is ambiguous and seems to depend on the properties of ligands. Type 3 interactions, which may lead to an increase in blood adsorption capacity and change in the pharmacokinet-ics of drugs used in combination with perfluorane, appear to be the most important. Key words: perfluorane, binding, drugs, drug interactions.Цель исследования — оценка сорбционной способности перфторана в отношении лекарственных веществ, принадлежащих к различным фармакологическим группам. Материалы и методы. В экспериментах in vitro с помощью метода равновесного диализа исследована степень связывания с перфтораном 50 лекарственных веществ, взятых в концентрациях от 12,5 до 100 мкМ. Результаты. Выявлены три типа взаимодействия лигандов с частицами эмульсии перфторана. Вещества первого типа характеризовались негативной тропностью к перфторану; ли-ганды второго типа вели себя индифферентно по отношению к эмульсии; соединения третьего типа обратимо сорбировались частицами кровезаменителя с константами взаимодействия Kag порядка 104 М-1. Заключение. Сорбционная активность перфторана в отношении лекарственных веществ проявляется неоднозначно и, по-видимому, зависит от свойств лигандов. Наиболее значимыми представляются взаимодействия третьего типа, результатом которых может стать увеличение сорбционной емкости крови и изменение фармакокинетики лекарств, используемых совместно с перфтораном. Ключевые слова: перфторан, связывание, лекарственные вещества, лекарственные взаимодействия

КЛИНИЧЕСКИЙ СЛУЧАЙ СИНДРОМА МИЛЛЕРА - ФИШЕРА В ПРАКТИКЕ ДЕТСКИХ ИНФЕКЦИОННЫХ БОЛЕЗНЕЙ

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