New reactions of sulphur dichloride with olefines

The interaction between SCl₂ and adamantylideneadamantane produces epithiocompounds $\text{2}$ and $\text{3}$ or polychloroadamantylideneadamantanes $\text{4}$–$\text{7}$ depending upon conditions. The structure of $\text{3}$ was determined by X-ray analysis.     

Complex dynamics and bifurcations in a Hamiltonian system having a transversal homoclinic orbit to a saddle focus

A Hamiltonian system having a saddle-focus singular point with a transversal homoclinic orbit is considered. The bifurcations that occur upon a variation of the Hamiltonian are studied. Reconstructions of a symbolic system describing the hyperbolic set are investigated. Bifurcations linked with the appearance of Smale horseshoes are pointed out. The results are applied to a system determining traveling-wave solutions of the Landau-Lifshitz equation. Multisolitons with any number of humps can exist.     

Solitary wave solutions of nonlocal sine-Gordon equations

In this paper a nonlocal generalization of the sine-Gordon equation, u(tt)+sin u=( partial differential / partial differential x) integral (- infinity ) (+ infinity )G(x-x('))u(x(') )(x('),t)dx(') is considered. We present a brief review of the applications of such equations and show that involving such a nonlocality can change features of the model. In particular, some solutions of the sine-Gordon model (for example, traveling 2pi-kink solutions) may disappear in the nonlocal model; furthermore, some new classes of solutions such as traveling topological solitons with topological charge greater than 1 may arise. We show that the lack of Lorenz invariancy of the equation under consideration can lead to a phenomenon of discretization of kink velocities. We discussed this phenomenon in detail for the special class of kernels G(xi)= summation operator (j=1) (N)kappa(j)e(-eta(j)mid R:ximid R:), eta(j)>0, j=1,2, em leader,N. We show that, generally speaking, in this case the velocities of kinks (i) are determined unambiguously by a type of kink and value(s) of kernel parameter(s); (ii) are isolated i.e., if c(*) is the velocity of a kink then there are no other kink solutions of the same type with velocity c in (c(*)- varepsilon,c(*)+ varepsilon ) for a certain value of varepsilon. We also used this special class of kernels to construct approximations for analytical and numerical study of the problem in a more general case. Finally, we set forth results of the numerical investigation of the problem with the kernel that is the McDonald function G(xi) approximately K(0)(mid R:ximid R:/lambda) (lambda is a parameter) that have applications in the Josephson junction theory. (c) 1998 American Institute of Physics.     

Light transmission through a circular metallic grating under broadband radial and azimuthal polarization illumination

We studied the characteristics of a circular metallic grating illuminated by broadband radial and azimuthal polarizations. We demonstrated that this scenario is the cylindrical analogue of a one-dimensional Cartesian grating illuminated by TM and TE polarizations. We measured the transmission spectra of this structure and observed strong polarization selectivity and, specifically, a resonance for radial polarization excitation, indicating a strong coupling to surface plasmons. The structure may be attractive for applications where pure radial polarization is needed, such as tight focusing, material processing, and particle trapping.     

Some aerodynamic and acoustic characteristicsof acute laryngitis

The purpose of the present study was to describe the effects ofacute laryngitis on some aerodynamic, acoustic, and perceptual measures. Eleven subjects with diagnosed acute laryngitis due to upper respiratory infection were recorded during a laryngitic episode and 1 week to 10 days after amelioration of the laryngitic condition. Fundamental frequency values, collapsed across the five vowels, were significantly reduced in the laryngitic compared with the normal speaking condition. The decrease in fundamental frequency associated with acute laryngitis suggests an increase in the mass of the vocal folds. In addition, aerodynamic values differed significantly for the laryngitic condition compared with the normal speaking condition, suggesting the presence of laryngeal hypofunction. Perceptual data indicated that speakers in the laryngitic condition were judged to have a hoarse voice when compared with the normal speaking condition.     

Group methodology in production management: A solution based on a hierarchical classification method

We consider the problem submitted by Garcia and Proth and we propose for it a solution obtained by simply applying our very general method of hierarchical classification based on the likelihood of the links, in the case of an incidence table of data. This application is done on each of the two sides of the incidence data table. In our approach, the common number p of classes has not to be fixed arbitrarily, but is an observed possible result—provided by the notions of ‘significant’ levels and nodes of the classification tree—for the ‘natural’ association between two partitions. We compare our solution with the previous one.     

NMR ANALYSES OF TRYPTOPHAN-8-METHOXYPSORALEN PHOTOREACTION PRODUCTS FORMED IN THE PRESENCE OF OXYGEN

Proton-made spectroscopy was performed on solutions of l -tryptophan and 8-mcthoxypsoralen (8-MOP) in either D₂O or DMSO-d₆ in the presence of oxygen before and after irradiation with 360 nm monochromatic light. Irradiation results in the loss of hydrogen atoms at the 3. 4 and 4'. 5' positions of 8-MOP and at the indole C₂ position of tryptophan. Changes in the aliphatic regions of the spectra also occur with irradiation. It is postulated that generation of photoreaction products between 8-MOP and tryptophan involves the 3.4 and 4'.5' positions of 8-MOP and the imidazole moiety of tryptophan.
Reprint requests to: Dr J. Megaw, Laboratory for Ophthalmic Research, Emory University School of Medicine, Atlanta. Georgia 30322. USA.     

Reactions of sulfur halides with unsaturated compounds. 26. Reactions of sulfur dichloride with tricyclo[4.2.2.02,5]deca-3,7-dienes and tricyclo[4.2.2.02,5]deca-3,7,9-trienes. Synthesis of compounds with a novel thiaskeletal structure

Addition of sulfur dichloride to tricyclo[4.2.2.0^{2, 5}]deca-3,7-dienes and tricyclo[4.2.2.0^2,5] deca-3,7,9-trienes is accompanied by intramolecular cyclization to give high yields of adducts with the novel thiaskeletal 7-thiatetracyclo[4.2.2.0^4,8.0^5,10]undecane structure. In the reaction of SCl₂ with the 2,3-endo, endo-diester (V), intramolecular cyclization is accompanied by lactonization, to give quantitative yields of the thiaskeletal chlorolactone (X). The structure of the latter compounds was established by x-ray diffraction examination.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 4, pp. 858–864, April, 1990.For previous commmunication see [1].     

Hamiltonian group actions on symplectic Deligne–Mumford stacks and toric orbifolds

We develop differential and symplectic geometry of differentiable Deligne–Mumford stacks (orbifolds) including Hamiltonian group actions and symplectic reduction. As an application we construct new examples of symplectic toric DM stacks.