Entropy, purity and optical hysteresis in markovian optical modes.

We describe the synthesis of optical modes whose axial structure follows a random tandem array of Bessel beams of integer order. The array follows fluctuations of Markov-chain type and the amplitude values for each beam are linked to a sequence of random vectors. As a prototype, we describe the synthesis of optical fields for Markov-chain type Ehrenfest. This process models the thermodynamic equilibrium and then it can be related to the evolution and stability of optical systems, in this way, it offers a similitude with partially coherent processes where the coherence degree is now distributed between all the compounds of the resulting random vector. The matrix representation for the stochastic process allows incorporating entropy properties and the calculus of the purity for the optical field. This constitutes the basis to describe the interference between markovian modes. When the set of markovian modes type Ehrenfest reaches a stable configuration they become indistinguishability non-conservative optical field having associated hysteresis features. Computer simulations are presented.

Stability of focusing regions and its vortex-solitonic properties.

Focusing regions, also known as caustic regions, are the singular solutions to the amplitude function of optical fields. Focusing regions are generated by the envelope curve of a set of critical points, which can be of attractor or repulsor type. The nature of the critical point depends on the refractive index. An important property of the critical points is that they present charge-like features. When a focusing region is generated in media with a random refractive index, current-like effects appear, and the evolution of the focusing regions follows a diffusion behavior. The morphology of the focusing regions may generate vortices or "eternal solutions" of solitonic type in a nonlinear medium. Herein, the condition under which these effects occur is analyzed and experimentally corroborated.

Invariant correlated optical fields driven by multiplicative noise.

We describe the evolution of a linear transmittance when it is perturbed with multiplicative noise; the evolution is approximated through an ensemble of random transmittances that are used to generate diffraction fields. The randomness induces a competition mechanism between noise and transmittance, and it is identified through the self-correlation function. We show that the geometry of the self-correlation function is a single peak preserved in the diffraction field that can be matched with localization-like effects. To corroborate the theoretical predictions, we perform an experiment using a linear grating where the noise is approximated by a stochastic Markov chain. Experimental results are shown.

Generation of long-range curved-surface plasmonic modes and their propagation through thin metal films in a tandem array.

We describe the generation of plasmonic modes that propagate in a curved trajectory. This is performed by masking a metal surface with two screens containing a randomly distributed set of holes that follow a Gaussian statistic. The diameter of the holes is less than the wavelength of the illuminating plane wave. By implementing scaling and rotations on each screen, we control the correlation trajectory and generate long-range curved plasmonic modes. The study is generalized for the transmission of a plasmonic mode propagating in a tandem array of thin metal films using the evanescent character of the electric field.

Topological properties of the interaction between focusing regions kind cusped.

We study here the cusped-cusped interaction between two kinds of Pearcey optical fields by analyzing its topological structure. We do it in two steps; the first one is an irradiance interaction that allows us to identify organization regions. The second one is an amplitude interaction, where it is shown that the interference fringes are organized around the irradiance distribution. The topological behavior of the optical field is analyzed identifying regions with different phase functions, one of them, corresponds with a catastrophe function which has associated a focusing region, the other region can be approximated by a quadratic function. The main consequence heritage from the phase structure is interference fringes emerge from focusing regions having similar features like a topological charges. We show computational and experimental results which are in very well agreement with the theoretical model.

Diffraction by three-dimensional slit-shape curves: decomposition in terms of Airy and Pearcey functions.

We analyze the diffraction field generated by coherent illumination of a three-dimensional transmittance characterized by a slit-shape curve. Generic features are obtained using the Frenet-Serret equations, which allow a decomposition of the optical field. The analysis is performed by describing the influence of the curvature and torsion on osculating, normal, and rectifying planes. We show that the diffracted field has a decomposition in three optical fields propagating along three optical axes that are mutually perpendicular. The decomposition is in terms of the Pearcey and Airy functions, and the generalized Airy function. Experimental results are shown.

Markovian optical modes.

We describe the transition of a set of optical modes following a Markov chain process, where the mean value of the amplitude converge to a new type of partially coherent mode, with the property that the coherence features are easily tunable with the parameters of the chain. The amplitude of the resulting mode depends on the probability transition of the chain. As a prototype, we establish an analogy with gambler's chain ruin, using as a basis for the vector space the Bessel modes of integer order. Computer simulations are shown.

Prostaglandin-oxytocin enhancement.

PIP: Dr. Arnold Gillespie (January 15, p.150) indicates that uterine contractions can be enhanced if oxytocin is given after previous exposure to prostaglandin E2 (PGE2). Brummer showed by in vitro experiments that after exposure to the PGE2, but not to the PGF2alpha, human myometrial strips exhibited an enhanced response to oxytocin. We report here preliminary results on the abortifacient effect of a combined treatment with PGF2alpha and oxytocin. The combined treatment, administered extraamniotically by means of a Foley catheter introduced between the fetal membranes and the uterine wall through the cervical canal, was given to 32 women admitted to the hospital for termination of midtrimester pregnancies. A dose of 0.5 mg PGF2alpha (Astra) was given hourly to 20 women. Higher doses (0.75-2.0 mg) were used if the uterine contractions were weak or lacking. 9 women received a mixture containing 0.5 mg of PGF2alpha and 1 I.U. of oxytocin, and 3 women received 3 I.U. of oxytocin alone. In the PGF2 alpha group of 20 patients, abortion was complete in 7 and incomplete in 10 cases. 3 failures were encountered. The trial was considered a failure if uterine contractions stopped in spite of continuous and increased dosage. In the group of 9 women who received a mixture of PGF2alpha and oxytocin, there was no failure. Abortion was complete in 5 and incomplete in 4 cases. Of the 3 women who received oxytocin only, 1 aborted and 2 failed. Uterine contractions were present in all 3 cases. The mean dose of PGF2alpha required for an abortion was 26.1 mg in the PG group, while that in the combined PGF2alpha and oxytocin group was 15.2 mg. 2 of 3 failures in the PG group were successfully treated with an intravenous oxytocin infusion (5 I.U./hour), which caused uterine contractions when PG had no further effect. Hysterotomy was needed in 1 case, where a bicornuate uterus was found at the operation. Extraamniotic oxytocin alone caused uterine contractions in all 3 cases included in the trial, although abortion was achieved in only 1 case. The 2 failures in the oxytocin group were treated with extraamniotic PG. In the total series of 32 cases, hysterotomy was not required in 31 (97%) if both PG and oxytocin were used. PGF2alpha and oxytocin have a contractile effect on the uterus in vivo during midtrimester. Whether the effects of these 2 drugs are additive or potentiative is now being studied.^ieng